This invention relates to the output circuit of a charge-coupled device (hereinafter referred to as "a CCD", when applicable) which is used for a comb filter, delay line, split-electrode type transversal filter, or the like.
A charge detecting method using floating gates have been generally employed to take the output signal of the CCD. For instance, in the case of a double-split electrode type transversal filter, the positive sense line and the negative sense line which are connected to the floating gates of the CCD are connected to input terminals of two operational amplifiers, respectively, the outputs of which are applied to another operational amplifier, so that the difference between these outputs is employed as the output voltage.
The output signal taking method may be used for a low frequency band of the order of 100 KHz, but not for a high frequency band covering video signals or the like. Furthermore, the obtained output DC voltage is always equal to the floating gate reset voltage of the CCD.